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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DERBY-5068) Investigate increased CPU usage on client after introduction of UTF-8 CcsidManager
Date Thu, 28 Apr 2011 23:28:04 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5068?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13026773#comment-13026773
] 

Dag H. Wanvik commented on DERBY-5068:
--------------------------------------

Good to understand! The patch adds some complexity by manually converting to UTF-8 "manually"
instead of using the Java libraries, though. If you think the performance increase is worth
the added complexity, it might be nice to add some links which explains the logic. Does the
logic work also if the string contains surrogate pairs?

> Investigate increased CPU usage on client after introduction of UTF-8 CcsidManager
> ----------------------------------------------------------------------------------
>
>                 Key: DERBY-5068
>                 URL: https://issues.apache.org/jira/browse/DERBY-5068
>             Project: Derby
>          Issue Type: Task
>    Affects Versions: 10.7.1.1
>            Reporter: Knut Anders Hatlen
>         Attachments: d5068-1a.diff
>
>
> While looking at the performance graphs for the single-record select test during the
last year - http://home.online.no/~olmsan/derby/perf/select_1y.html - I noticed that there
was a significant increase (10-20%) in CPU usage per transaction on the client early in October
2010. To be precise, the increase seems to have happened between revision 1004381 and revision
1004794. In that period, there were three commits: two related to DERBY-4757, and one related
to DERBY-4825 (tests only).
> We should try to find out what's causing the increased CPU usage and see if there's some
way to reduce it.

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